#include <51func.h>
int main(int argc, char *argv[])
{
    // ./11_file_length file1
    ARGS_CHECK(argc,2);
    int fd = open(argv[1],O_RDWR);
    ERROR_CHECK(fd,-1,"open");
    off_t length = lseek(fd,0,SEEK_END);
    printf("length = %ld\n", length);
    close(fd);
    return 0;
}

